Magnetic core, three-phase transformer and power conversion device comprising three-phase transformer
By optimizing the core structure and component arrangement, combining three-phase coils and switching units, the problems of large volume and poor electromagnetic compatibility of the core and transformers in the on-board charger of new energy vehicles are solved, and the volume reduction and efficiency improvement of the device are achieved.
Patent Information
- Application Number
- CN202420153276.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-22
- Publication Date
- 2024-12-20
- Estimated Expiration
- 2034-01-22
AI Technical Summary
The existing magnetic core and three-phase transformers are large in vehicle-mounted chargers for new energy vehicles, and have problems with thermal problems and poor electromagnetic compatibility.
A magnetic core including a first magnetic core assembly and a second magnetic core assembly is designed, and a structure of a first side column group, a second side column group and a middle column group is adopted. The arrangement of the magnetic core is optimized through gaps and air gaps, combined with The three-phase coil and switching unit form a three-phase transformer and power conversion device, reducing volume and improving energy conversion efficiency and electromagnetic compatibility performance.
It has achieved the reduction of device volume, the improvement of energy conversion efficiency and the improvement of electromagnetic compatibility performance, and is suitable for vehicle-mounted chargers of new energy vehicles.
Smart Images
Figure CN222213891U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of power supply, and in particular to a magnetic core, a three-phase transformer and a power conversion device including the same. Background Art
[0002] With the rapid development of new energy vehicles, the proportion of new energy vehicles is increasing.
[0003] New energy vehicles have power batteries as power sources, and the input end of the on-board charger (OBC) needs to be directly connected to the power grid to charge the power battery through power conversion. In order to implement the concept of green energy development, the on-board charger, as an energy conversion device between the battery of new energy vehicles and the power grid, is gradually developing towards low carbon footprint, high conversion efficiency, and high power density. Automobile terminals are gradually moving towards integration and integration.
[0004] In order to pursue high efficiency and high power density on-board chargers, passive components are the core components of on-board chargers. The volume of passive components such as transformers and inductors occupies more than 1 / 3 of the entire charger volume. By increasing the frequency, the volume of magnetic components can be reduced and the power density of the on-board charger can be increased, but it also brings many thermal problems and electromagnetic compatibility (EMC) problems of magnetic components. Magnetic integration usually refers to the integration of inductors and transformers, or the integration of inductors and inductors, transformers and transformers, etc. Magnetic integration can not only reduce the volume, but also reduce magnetic field emission and reduce the interference of leakage magnetic fields on other components. At the same time, it can ensure high efficiency of energy conversion, meet market demand, and reduce carbon emissions. Utility Model Content
[0005] The technical problem to be solved by the utility model is: how to reduce the volume of the magnetic core or the three-phase transformer or the power conversion device, improve the efficiency of energy conversion, and enhance the electromagnetic compatibility performance.
[0006] In order to solve the above technical problems, the utility model provides a magnetic core, a three-phase transformer and a power conversion device including the same, the purpose of which is to reduce the volume, improve the energy conversion efficiency and improve the electromagnetic compatibility performance.
[0007] In order to achieve the above object, the utility model provides a magnetic core, comprising:
[0008] A first magnetic core component, the first magnetic core component comprises a first magnetic block, a first side column group, a second side column group and a middle column group; the first ends of the first side column group, the second side column group and the middle column group are connected to the first magnetic block; the middle column group is located between the first side column group and the second side column group; the first side column group comprises three first side columns, each of which has a gap between them; the second side column group comprises three second side columns, each of which has a gap between them; the middle column group comprises three middle columns, each of which has a gap between them;
[0009] The second magnetic core component comprises a second magnetic block, the second ends of the first side column group and the second side column group are connected to the second magnetic block, and an air gap is formed between the second magnetic block and the second end of the middle column group.
[0010] Preferably, the lengths of the first side pillars and the second side pillars are equal; the lengths of the middle pillars are equal.
[0011] Preferably, three first side pillars are arranged in a row, three second side pillars are arranged in a row, three middle pillars are arranged in a row, and one first side pillar, one second side pillar and one middle pillar are arranged in a column to form three columns of first side pillars, second side pillars and middle pillars.
[0012] Preferably, the second magnetic block includes three second single-phase magnetic blocks, each of which has a gap between them; each second single-phase magnetic block is aligned with a column of first side columns, second side columns and middle columns and is connected to the second ends of the first side columns and the second side columns.
[0013] In order to achieve the above object, the utility model also provides a three-phase transformer, comprising:
[0014] The aforementioned magnetic core;
[0015] Three-phase first coils, wherein each first side column is wound with a first coil of one phase;
[0016] The three-phase second coils are each wound with a one-phase second coil on each second side pole.
[0017] In order to achieve the above object, the utility model also provides a power conversion device, comprising:
[0018] The aforementioned three-phase transformer;
[0019] A first switch unit, wherein the first switch unit is connected to a three-phase first coil;
[0020] A second switch unit is connected to the three-phase second coil.
[0021] Preferably, the first switch unit comprises a first switch bridge arm, a second switch bridge arm and a third switch bridge arm connected in parallel, the first switch bridge arm, the second switch bridge arm and the third switch bridge arm each comprise two switch tubes connected in series, and the first ends of the three-phase first coils are respectively connected to the common nodes of the first switch bridge arm, the second switch bridge arm and the third switch bridge arm;
[0022] The second switch unit includes a fourth switch bridge arm, a fifth switch bridge arm and a sixth switch bridge arm connected in parallel, and the fourth switch bridge arm, the fifth switch bridge arm and the sixth switch bridge arm each include two switch tubes connected in series, and the first ends of the three-phase second coils are respectively connected to the common nodes of the fourth switch bridge arm, the fifth switch bridge arm and the sixth switch bridge arm.
[0023] Preferably, the second end of the first-phase second coil is connected to the second end of the second-phase second coil via a resonant capacitor; the second end of the second-phase second coil is connected to the second end of the third-phase second coil via a resonant capacitor; the second end of the third-phase second coil is connected to the second end of the first-phase second coil via a resonant capacitor.
[0024] Preferably, the second end of the first coil of the first phase is connected to the second end of the first coil of the second phase through a resonant capacitor; the second end of the first coil of the second phase is connected to the second end of the first coil of the third phase through a resonant capacitor; the second end of the first coil of the third phase is connected to the second end of the first coil of the first phase through a resonant capacitor.
[0025] Preferably, the three-phase transformer generates three resonant inductors, and the three resonant inductors are determined by the sizes of the air gaps between the three second magnetic blocks and the corresponding three middle columns.
[0026] Compared with the prior art, the utility model provides a magnetic core, including: a first magnetic core component, the first magnetic core component includes a first magnetic block, a first side column group, a second side column group and a middle column group; the first ends of the first side column group, the second side column group and the middle column group are connected to the first magnetic block; the middle column group is located between the first side column group and the second side column group; the first side column group includes three first side columns, and there is a gap between each first side column; the second side column group includes three second side columns, and there is a gap between each second side column; the middle column group includes three middle columns, and there is a gap between each middle column; the second magnetic core component includes a second magnetic block, the second ends of the first side column group and the second side column group are connected to the second magnetic block, and an air gap is formed between the second magnetic block and the second end of the middle column group. The utility model also provides a three-phase transformer, including: the aforementioned magnetic core; a three-phase first coil, wherein each first side column is wound with a first phase coil; a three-phase second coil, wherein each second side column is wound with a second phase coil. The utility model also provides a power conversion device, including: the above-mentioned three-phase transformer; a first switch unit, the first switch unit is connected to the three-phase first coil; a second switch unit, the second switch unit is connected to the three-phase second coil. Therefore, compared with the prior art, the technical effect that the utility model can achieve is to reduce the volume of the device, improve the energy conversion efficiency, and improve the electromagnetic compatibility performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0028] Figure 1 An exploded view of a first embodiment of a magnetic core provided by the utility model is shown.
[0029] Figure 2 An exploded view of a second embodiment of the magnetic core provided by the utility model is shown.
[0030] Figure 3 A side view schematic diagram of a second embodiment of the magnetic core provided by the utility model is shown.
[0031] Figure 4 An exploded view of a first embodiment of a three-phase transformer provided by the utility model is shown.
[0032] Figure 5 An exploded view of a second embodiment of a three-phase transformer provided by the utility model is shown.
[0033] Figure 6The structural schematic diagram of the second embodiment of the three-phase transformer provided by the utility model is shown.
[0034] Figure 7 The present invention shows an equivalent circuit diagram of one phase of the three-phase transformer when it is applied to a power conversion device.
[0035] Figure 8 The circuit connection diagram of the power conversion device provided by the utility model is shown. DETAILED DESCRIPTION
[0036] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.
[0037] It should be understood that the terms "first", "second", etc. in the claims, specification and drawings of the present application are used to distinguish different objects rather than to describe a specific order. The terms "include" and "comprise" used in the specification and claims of the present application indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections.
[0038] See also Figure 1 , Figure 2 and Figure 3 As shown, the magnetic core 8 provided by the utility model includes: a first magnetic core component 1 and a second magnetic core component 2. The first magnetic core component 1 includes a first magnetic block 3, a first side column group 4, a second side column group 5 and a middle column group 6. The first ends of the first side column group 4, the second side column group 5 and the middle column group 6 are connected to the first magnetic block 3. The middle column group 6 is located between the first side column group 4 and the second side column group 5. The first side column group 4 includes a first side column 4a, a first side column 4b and a first side column 4c, and there is a gap between the first side column 4a, the first side column 4b and the first side column 4c. The second side column group 5 includes a second side column 5a, a second side column 5b and a second side column 5c, and there is a gap between the second side column 5a, the second side column 5b and the second side column 5c. The middle column group 6 includes a middle column 6a, a middle column 6b and a middle column 6c, and there is a gap between the middle column 6a, the middle column 6b and the middle column 6c. The second magnetic core assembly 2 includes a second magnetic block 7, the second ends of the first side column group 5 and the second side column group 6 are connected to the second magnetic block 7, and air gaps 12a, 12b and 12c are formed between the second magnetic block 7 and the second end of the middle column group 6.
[0039] See also Figure 1 and Figure 2As shown, the lengths of the first side column 4a, the first side column 4b, the first side column 4c and the second side column 5a, the second side column 5b, the second side column 5c are equal. The lengths of the middle column 6a, the middle column 6b, the middle column 6c are equal. The lengths of the middle column 6a, the middle column 6b, the middle column 6c are less than the lengths of the first side column 4a, the first side column 4b, the first side column 4c, the second side column 5a, the second side column 5b, the second side column 5c. Accordingly, air gaps 12a, 12b, and 12c are formed between the second magnetic block 7 and the second end of the middle column group 6.
[0040] See also Figure 1 and Figure 2 As shown, the first side column 4a, the first side column 4b, and the first side column 4c are arranged in a row, the second side column 5a, the second side column 5b, and the second side column 5c are arranged in a row, and the middle column 6a, the middle column 6b, and the middle column 6c are arranged in a row. The first side column 4a, the second side column 5a, and the middle column 6a are arranged in a column, the first side column 4b, the second side column 5b, and the middle column 6b are arranged in a column, and the first side column 4c, the second side column 5c, and the middle column 6c are arranged in a column, forming three columns of the first side column, the second side column, and the middle column, that is, forming an arrangement of three rows and three columns. However, the present application is not strictly limited to three neat rows and three columns, and generally three rows and three columns are sufficient.
[0041] See also Figure 2 As shown, the second magnetic block 7 includes a second single-phase magnetic block 7a, a second single-phase magnetic block 7b, and a second single-phase magnetic block 7c. There is a gap between the second single-phase magnetic block 7a, the second single-phase magnetic block 7b, and the second single-phase magnetic block 7c. The second single-phase magnetic block 7a is aligned with the first side column 4a, the second side column 5a, and the middle column 6a and is connected to the second ends of the first side column 4a and the second side column 5a; the second single-phase magnetic block 7b is aligned with the first side column 4b, the second side column 5b, and the middle column 6b and is connected to the second ends of the first side column 4b and the second side column 5b; the second single-phase magnetic block 7c is aligned with the first side column 4c, the second side column 5c, and the middle column 6c and is connected to the second ends of the first side column 4c and the second side column 5c. That is, each second single-phase magnetic block is aligned with a column of the first side column, the second side column, and the middle column and is connected to the second ends of the first side column and the second side column.
[0042] See also Figure 4 , Figure 5 and Figure 6As shown, the three-phase transformer 9 provided by the utility model comprises: a magnetic core 8. A first coil 10a of a single phase is wound on the first side column 4a; a first coil 10b of a single phase is wound on the first side column 4b; a first coil 10c of a single phase is wound on the first side column 4c. A second coil 11a of a single phase is wound on the second side column 5a; a second coil 11b of a single phase is wound on the second side column 5b; a second coil 11c of a single phase is wound on the second side column 5c. In this way, a three-phase transformer 9 is formed, and air gaps 12a, 12b, 12c are formed between the second ends of the middle column 6a, the middle column 6b, the middle column 6c and the second magnetic block 7 (7a, 7b, 7c). Figure 6 Only the air gap 12c is shown in the figure. It should be understood that the other air gaps 12a and 12b are not shown because they are blocked by the viewing angle of the stereoscopic view. Figure 4 The structural explosion diagram of an embodiment of the corresponding three-phase transformer 9 includes the corresponding Figure 1 An embodiment of the magnetic core 8. Figure 5 The structural explosion diagram of another embodiment of the corresponding three-phase transformer 9 includes the corresponding Figure 2 Another embodiment of the magnetic core 8, Figure 6 For the corresponding Figure 5 The exploded diagram of the components is combined into a schematic diagram of the three-phase transformer 9.
[0043] See also Figure 8 As shown, the power conversion device provided by the utility model includes: a three-phase transformer 9, a first switch unit 13, and a second switch unit 14. The first switch unit 13 is connected to the three-phase first coils 10a, 10b, and 10c. The second switch unit 14 is connected to the three-phase second coils 11a, 11b, and 11c.
[0044] The first switch unit 13 and the second switch unit 14 each include at least one switch tube, and realize the DC voltage source V by controlling the on and off of the switch tube in the switch unit together with the three-phase transformer 9. in and battery voltage V bat The conversion between the battery voltage V bat That is, it is used to charge the power batteries in new energy vehicles.
[0045] In one specific embodiment, see Figure 8As shown, the first switch unit 13 includes a first switch bridge arm, a second switch bridge arm and a third switch bridge arm connected in parallel. The first switch bridge arm includes a switch tube Q1 and a switch tube Q2 connected in series, and the connection point A of the switch tube Q1 and the switch tube Q2 forms a common node A of the first switch bridge arm, and the common node A is connected to the first end of the first coil 10a of the first phase. The second switch bridge arm includes a switch tube Q3 and a switch tube Q4 connected in series, and the connection point B of the switch tube Q3 and the switch tube Q4 forms a common node B of the second switch bridge arm, and the common node B is connected to the first end of the first coil 10b of the second phase. The third switch bridge arm includes a switch tube Q5 and a switch tube Q6 connected in series, and the connection point C of the switch tube Q5 and the switch tube Q6 forms a common node C of the third switch bridge arm, and the common node C is connected to the first end of the first coil 10c of the third phase.
[0046] See also Figure 8 As shown, the second end of the first coil 10a of the first phase, the second end of the first coil 10b of the second phase, and the second end of the first coil 10c of the third phase are connected together. Not shown in the figure, this connection method is also applicable to the connection of the second coils 11a, 11b, 11c.
[0047] See also Figure 8 As shown, a capacitor C is connected between the common node A of the first switch bridge arm and the first end of the first coil 10a of the first phase. bp1 The common node B of the second switch bridge arm and the first end of the first coil 10a of the first phase are connected through a capacitor C bp2 The common node C of the third switch bridge arm and the first end of the first coil 10a of the first phase are connected through a capacitor C bp3 Not shown in the figure, this connection method is also applicable to the connection of the second coils 11a, 11b, 11c. bp1 , capacitor C bp2 , capacitor C bp3 It is a DC blocking capacitor.
[0048] See also Figure 8 As shown, the second switch unit 14 includes a fourth switch bridge arm, a fifth switch bridge arm and a sixth switch bridge arm connected in parallel. The fourth switch bridge arm includes a switch tube Q7 and a switch tube Q8 connected in series, and the connection point E of the switch tube Q7 and the switch tube Q8 forms a common node E of the fourth switch bridge arm, and the common node E is connected to the first end of the second coil 11a of the first phase. The fifth switch bridge arm includes a switch tube Q9 and a switch tube Q10 connected in series. 10 , switch tube Q9 and switch tube Q 10 The connection point F forms a common node F of the fifth switch bridge arm, and the common node F is connected to the first end of the second coil 11b of the second phase. The sixth switch bridge arm includes switch tubes Q connected in series. 11 And the switch tube Q12 , switch tube Q 11 And the switch tube Q 12 The connection point G forms a common node G of the sixth switching bridge arm, and the common node G is connected to the first end of the second coil 11c of the second phase.
[0049] See also Figure 8 As shown, the second end of the first phase second coil 11a is connected to the resonant capacitor C rs1 The second end of the second phase second coil 11b is connected to the second end of the second phase second coil 11b. The second end of the second phase second coil 11b is connected to the second end of the second phase second coil 11b through the resonant capacitor C rs2 The second end of the third phase second coil 11c is connected to the second end of the third phase second coil 11c. The second end of the third phase second coil 11c is connected to the second end of the third phase second coil 11c through the resonant capacitor C rs3 Connected to the second end of the first-phase second coil 11 a.
[0050] Not shown in the figure, corresponding to the above embodiment, it can also be applied to the first coils 10a, 10b, 10c. The second end of the first coil of the first phase is connected to the second end of the first coil of the second phase through a resonant capacitor; the second end of the first coil of the second phase is connected to the second end of the first coil of the third phase through a resonant capacitor; the second end of the first coil of the third phase is connected to the second end of the first coil of the first phase through a resonant capacitor.
[0051] In practical applications, see Figure 8 As shown, a bulk capacitor (large capacitor) C1 is connected in parallel with the first switch bridge arm, the second switch bridge arm and the third switch bridge arm, and a bulk capacitor (large capacitor) C2 is connected in parallel with the fourth switch bridge arm, the fifth switch bridge arm and the sixth switch bridge arm.
[0052] DC V in and DC V bat One is the input DC power and the other is the output DC power. Figure 8 As shown, one embodiment is shown, V in It is the input source of the three-phase AC power of the mains or the single-phase AC power of the mains converted into DC power by the converter; V bat A DC power source for charging the power battery.
[0053] See also Figure 7As shown, the equivalent circuit connection of one phase of the three-phase transformer 9 is shown. The three-phase transformer 9 generates three resonant inductors Lrs1, Lrs2, and Lrs3. Since the magnetic resistance of the air gap between the middle column and the second magnetic block is much greater than the magnetic resistance at the magnetic core of the first side column, the second side column, the middle column, the first magnetic block, the second magnetic block, etc., the three resonant inductors Lrs1, Lrs2, and Lrs3 are generated by the air gaps 12a, 12b, and 12c between the three second magnetic blocks 7a, 7b, and 7c and the corresponding three middle columns 6a, 6b, and 6c, and are determined by the size of the air gaps 12a, 12b, and 12c. The resonant inductor Lrs1 is connected in series with the second coil 11a; the resonant inductor Lrs2 is connected in series with the second coil 11b; and the resonant inductor Lrs3 is connected in series with the second coil 11c. The sizes of the air gaps 12a, 12b, and 12c can be equal or unequal.
[0054] Resonant inductors Lrs1, Lrs2, Lrs3 and resonant capacitors C rs1 , C rs2 , C rs3 Connected to form a resonant unit, the switch unit on the side of the resonant unit can achieve soft switching. Figure 8 As shown, a resonance unit is formed on the side of the second switch unit 14, and the switch tube in the second switch unit 14 can realize soft switching. Of course, a resonant capacitor can also be connected to the side of the first switch unit 13, and a resonance unit is formed on the side of the first switch unit 13, and the switch tube in the first switch unit 13 can realize soft switching. Or a resonance unit is formed on both sides, and the switch tubes in the first switch unit 13 and the second switch unit 14 can realize soft switching.
[0055] The resonant inductances Lrs1 and Lrs2 generated by the adjacent middle poles 6a and 6b are coupled by magnetic flux, and the resonant inductances Lrs2 and Lrs3 generated by the adjacent middle poles 6b and 6c are coupled by magnetic flux.
[0056] The technical effect of the magnetic core, three-phase transformer and power conversion device including the same provided by the utility model is that, when applied to a vehicle charger, the volume of the device is reduced, the energy conversion efficiency is improved, and the electromagnetic compatibility performance is improved.
[0057] The above specific embodiments and accompanying drawings are only used to illustrate the technical solutions and technical effects of the utility model, and are not used to limit the utility model. Any person skilled in the art who is familiar with this technology can modify or change the above embodiments within the scope of the claims without violating the technical principles and spirit of the utility model, and all of them belong to the scope of protection of the utility model.
Claims
1. A magnetic core, characterized in that: include: A first magnetic core component, the first magnetic core component comprises a first magnetic block, a first side column group, a second side column group and a middle column group; the first ends of the first side column group, the second side column group and the middle column group are connected to the first magnetic block; the middle column group is located between the first side column group and the second side column group; the first side column group comprises three first side columns, each of which has a gap between them; the second side column group comprises three second side columns, each of which has a gap between them; the middle column group comprises three middle columns, each of which has a gap between them; The second magnetic core component comprises a second magnetic block, the second ends of the first side column group and the second side column group are connected to the second magnetic block, and an air gap is formed between the second magnetic block and the second end of the middle column group.
2. The magnetic core according to claim 1, characterized in that The lengths of the first side columns and the second side columns are equal; the lengths of the middle columns are equal.
3. The magnetic core according to claim 1 or 2, characterized in that: Three first side pillars are arranged in a row, three second side pillars are arranged in a row, three middle pillars are arranged in a row, and one first side pillar, one second side pillar and one middle pillar are arranged in a column, forming three columns of first side pillars, second side pillars and middle pillars.
4. The magnetic core according to claim 3, characterized in that The second magnetic block includes three second single-phase magnetic blocks, each of which has a gap between them; each second single-phase magnetic block is aligned with a column of first side columns, second side columns and middle columns and is connected to the second ends of the first side columns and the second side columns.
5. A three-phase transformer, characterized in that: include: The magnetic core according to claim 1; Three-phase first coils, wherein each first side column is wound with a first coil of one phase; The three-phase second coils are each wound with a one-phase second coil on each second side pole.
6. A power conversion device, characterized in that: include: The three-phase transformer according to claim 5; A first switch unit, wherein the first switch unit is connected to a three-phase first coil; A second switch unit is connected to the three-phase second coil.
7. The power conversion device according to claim 6, characterized in that: The first switch unit comprises a first switch bridge arm, a second switch bridge arm and a third switch bridge arm connected in parallel, the first switch bridge arm, the second switch bridge arm and the third switch bridge arm each comprise two switch tubes connected in series, and the first ends of the three-phase first coils are respectively connected to the common nodes of the first switch bridge arm, the second switch bridge arm and the third switch bridge arm; The second switch unit includes a fourth switch bridge arm, a fifth switch bridge arm and a sixth switch bridge arm connected in parallel, and the fourth switch bridge arm, the fifth switch bridge arm and the sixth switch bridge arm each include two switch tubes connected in series, and the first ends of the three-phase second coils are respectively connected to the common nodes of the fourth switch bridge arm, the fifth switch bridge arm and the sixth switch bridge arm.
8. The power conversion device according to claim 7, characterized in that: The second end of the first-phase second coil is connected to the second end of the second-phase second coil via a resonant capacitor; the second end of the second-phase second coil is connected to the second end of the third-phase second coil via a resonant capacitor; the second end of the third-phase second coil is connected to the second end of the first-phase second coil via a resonant capacitor.
9. The power conversion device according to claim 7 or 8, characterized in that: The second end of the first coil of the first phase is connected to the second end of the first coil of the second phase through a resonant capacitor; the second end of the first coil of the second phase is connected to the second end of the first coil of the third phase through a resonant capacitor; the second end of the first coil of the third phase is connected to the second end of the first coil of the first phase through a resonant capacitor.
10. The power conversion device according to claim 1, characterized in that: The three-phase transformer generates three resonant inductors, which are determined by the sizes of the air gaps between the three second magnetic blocks and the corresponding three middle columns.